Microstructures and Properties of Ni–Cr–P Filler Metals and Brazed Joints Bearing CNTs

Abstract

In this paper, the effects of small amounts (0∼1.0 wt%) of carbon nanotubes (CNTs) on the microstructures and properties of Ni–Cr–P filler metal and brazed joints have been investigated. Various content of CNTs were successfully blended into Ni–Cr–P paste for preparation novel filler metals, the results indicate that small amount of CNTs can increase the melting temperature ∼3°C, enhance the wettability of filler metals on steel substrate, and improve the shear strength of brazed joints. Moreover, the microstructures can be refined obviously. However, excessive addition of CNTs will induce the nano-agglomeration, which degrade the wettability of filler metals and shear strength of brazed joints, coarsen the microstructures. Based on the optimization content of CNTs, 0.1% CNTs can maximize the properties of filler metals and brazed joints.